1. Field of the Invention
The present invention relates to a camera and shutter device. More particularly, the present invention relates to a camera in which an aperture stop is changed over according to object brightness, and an exposure is taken after the aperture stop is set, and a shutter device.
2. Description Related to the Prior Art
A lens-fitted photo film unit is known in the field of photograph as a camera of simple type, and pre-loaded with photo film in the course of manufacture. A lens in the lens-fitted photo film unit is a fixed focus type for the purpose of reducing a cost and structure. For the same purpose, a shutter in the lens-fitted photo film unit is a knocking type in which a shutter blade opens and shuts upon knocking operation, and of which a shutter speed is fixed. However, brightness of a photographic object may be totally different between various types of scene to be photographed. The brightness may be very low because of weak illumination in an indoor scene, or very high because of strong illumination in an outdoor scene. An exposure amount must be adjusted for the purpose of an exposure in any level of brightness. There has been a suggested lens-fitted photo film unit in which a photometric circuit is incorporated for measuring object brightness, and an exposure amount can be adjusted by changing over an aperture stop mechanism according to the measured object brightness.
The aperture stop changer device includes CdS element, solar cell or other photometric elements for measuring light from a photographic object to obtain object brightness. The object brightness is compared with reference brightness level, to drive a solenoid to set an aperture stop plate into or out of a photographic light path automatically. The measurement of object brightness is synchronized with turning on of the photometric switch by means of switching member movable in response to depression of a shutter release button. A widely used type of the photometric switch is a leaf switch because of a simple structure and a low cost. A pair of switch segments constitute the leaf switch, have conductivity and flexibility. A first one of the segments is depressed and caused to contact a second one of those, to turn on the photometric switch. When those segments are away from one another, the photometric switch is turned off.
However, it is likely in the known camera that the photometric switch in a form of leaf switch is turned on accidentally upon occurrence of external shock or vibration to a camera body. The photometric circuit and solenoid may be actuated in connection with the photometric switch.
In view of the foregoing problems, an object of the present invention is to provide a camera in which measurement of object brightness to change over the aperture stop can be effected safely without being influenced by shock or vibration, and a shutter device.
Another object of the present invention is to provide a camera in which a shutter mechanism can be actuated stably with sufficient delay time, and a shutter device.
A further object of the present invention is to provide a camera in which assembly of relevant elements can be facilitated even in a structure with a flash unit and an aperture stop changer mechanism, and a shutter device.
Still another object of the present invention is to provide a camera in which plural units in which relevant elements are combined can ensure suitability to recycling by disassembly and assembly, and a shutter device.
In order to achieve the above and other objects and advantages of this invention, a camera includes an aperture stop mechanism for changing over a photographic light path of object light between plural stop states, a depressible shutter release button, and a shutter mechanism for being released in response to depression of the shutter release button after a charging operation and changing over the aperture stop mechanism, to provide an exposure to the photo film. In the camera, a photometric circuit measures object brightness adapted for changing over the aperture stop mechanism. A photometric switch includes first and second switch segments, is turned on when pressed, to supply the photometric circuit with power. A first blocking mechanism blocks and turns off the first and second switch segments upon completion of the charging operation of the shutter mechanism, and comes away from the photometric switch when the shutter release button is depressed. A shifting mechanism presses and turns on the photometric switch after the first blocking mechanism comes away from the photometric switch.
Furthermore, a second blocking mechanism blocks the first and second switch segments from one another when the shutter mechanism is actuated, to keep the photometric switch turned off until a start of the charging operation of the shutter mechanism.
Furthermore, a delay mechanism is shifted to a charged position by winding operation of the photo film, and is shifted to a released position in response to the depression of the shutter release button, to actuate the shutter mechanism. The first blocking mechanism is moved according to shifting of the delay mechanism, keeps the photometric switch turned off when the delay mechanism is in the charged position, and comes away from the photometric switch when the delay mechanism is in the released position.
Furthermore, a switch gear rotates according to shifting of the delay mechanism. The first blocking mechanism is a blocking pin, the shifting mechanism is a shifting projection, and the blocking pin and the shifting projection are formed to protrude from the switch gear.
The first switch segment is offset from a moving path of the blocking pin and the shifting projection, and is free therefrom. The second switch segment has a portion disposed in the moving path, has a springy characteristic, is pushed by the shifting projection while the delay mechanism is shifted between the charged and released positions, and subsequently returns to an original state with resiliency.
The delay mechanism includes a tooth train portion having plural teeth arranged along an arc. Furthermore, a transmission gear portion is formed with the switch gear, meshed with the tooth train portion, for rotating.
The delay mechanism includes a delay lever movable pivotally. The second blocking mechanism is a second blocking pin formed to protrude from the delay lever.
It is therefore possible that measurement of object brightness to change over the aperture stop is effected safely without being influenced by shock or vibration, because the first blocking mechanism reliably blocks and turns off the first and second switch segments.
According to another aspect of the invention, a shutter device comprises a shutter release button. A delay lever moves from a charged position toward a released position in response to depression of the shutter release button, and reaches the released position upon lapse of a delay time. A shutter drive lever moves from a first position toward a second position when the delay lever reaches the released position. A shutter blade is driven by the shutter drive lever moving toward the second position, for opening and shutting a light path. A friction mechanism provides braking operation to the delay lever by frictional contact therewith, to set the delay time long.
Furthermore, a tooth train portion is formed with the delay lever. A governor mechanism is meshed with the tooth train portion, for regulating rotation at a predetermined speed, to set the delay time long.
The friction mechanism includes a bias spring for biasing the shutter drive lever toward the second position. A friction portion is formed with the shutter drive lever, and pressed against the delay lever by the bias spring.
The governor mechanism includes a transmission gear portion, meshed with the tooth train portion, for rotating. An escapement wheel portion is formed with the transmission gear portion, for constituting a switch gear. An ankle member is meshed with the escapement wheel portion, for restricting rotation thereof.
Thus, it is possible that the shutter mechanism is actuated stably with sufficient delay time, because the friction mechanism frictionally contacts to the delay lever.
According to a further aspect of the invention, a camera having a flash circuit board is provided. A large stop opening is disposed in a light path in a stationary manner. A movable aperture stop plate has a small stop opening smaller than the large stop opening, being movable between a large aperture position and a small aperture position, the movable aperture stop plate, when in the large aperture position, being offset from the light path, and when in the small aperture position, setting the small stop opening in the light path. An aperture stop plate shifter is secured to the flash circuit board, for shifting the movable aperture stop plate between the large aperture position and the small aperture position.
Furthermore, a photometric circuit measures brightness of a photographic object, and determines whether the brightness is low brightness lower than a predetermined level, or is high brightness equal to or higher than the predetermined level. The aperture stop plate shifter sets the movable aperture stop plate in the large aperture position if the low brightness is determined, and sets the movable aperture stop plate in the small aperture position if the high brightness is determined.
Furthermore, there is a depressible shutter release button. A shutter mechanism is released in response to depression of the shutter release button after a charging operation and changing over the movable aperture stop plate, to provide an exposure to the photo film. A synchronizing mechanism synchronizes the shutter mechanism with the aperture stop plate shifter, to disable the movable aperture stop plate from shifting upon completion of the charging of the shutter mechanism, to cause the movable aperture stop plate to shift after the depression of the shutter release button and before starting an exposing operation of the shutter mechanism, and to keep the movable aperture stop plate shifted during the exposing operation of the shutter mechanism.
The aperture stop plate shifter includes a stop changer lever, movable between first and second angular positions, for shifting the movable aperture stop plate when in the first angular position, and for coming away from the movable aperture stop plate when in the second angular position. A movable stopper shifts between a disabling position and an enabling position according to an output of the photometric circuit, to keep the stop changer lever in the first angular position when in the disabling position, and to enable the stop changer lever to shift to the second angular position when in the enabling position.
Furthermore, a delay lever rotates from a charged position to a released position in response to the depression of the shutter release button, for actuating the shutter mechanism with delay. The synchronizing mechanism includes a switch gear for being rotated by the delay lever. A transmission lever shifts the stop changer lever by rotating. A retention ridge is formed to protrude from the switch gear, for retaining the transmission lever when the delay lever is in the charged position, and for releasing and enabling the transmission lever to rotate when the delay lever is in the released position.
The movable stopper includes a solenoid. A stopper lever is moved by the solenoid, offset from a moving path of the stop changer lever when in the enabling position, and set in the moving path when in the disabling position.
Furthermore, a support member is secured fixedly to the flash circuit board, for supporting the stop changer lever and the movable stopper.
Furthermore, an operable button member is disposed to emerge outside a camera body, for shifting the stop changer lever between the first and second angular positions.
It is therefore possible that assembly of relevant elements is facilitated even in a structure with a flash unit and an aperture stop changer mechanism, because the aperture stop plate shifter is secured to the flash circuit board.
According to still another aspect of the invention, a camera includes a flash emitter for applying flash light to a photographic object, a taking lens for introducing object light from the object, an aperture stop mechanism for changing over a light path of the object light between plural stop states, an aperture stop actuator for driving the aperture stop mechanism, a shutter mechanism for providing an exposure to photo film with the object light. In the camera, an exposure unit includes the shutter mechanism. A flash unit includes the flash emitter and the aperture stop actuator. A lens unit is secured to a front of the exposure unit, and includes the taking lens and the aperture stop mechanism.
Furthermore, a depressible shutter release button is adapted for releasing the shutter mechanism. The exposure unit further includes a light-shielded tunnel for covering the light path, and having the shutter mechanism secured thereto. A shifting mechanism moves from an off-position to an on-position after depression of the shutter release button and before completion of releasing the shutter mechanism. The flash unit further includes a photometric circuit for measuring object brightness of the object, and for outputting a signal for controlling the aperture stop actuator according to the object brightness. A photometric switch is turned on in response to movement of the shifting mechanism to the on-position, to supply the photometric circuit with power.
The camera is a lens-fitted photo film unit. Furthermore, a main body has a cassette holder chamber and a photo film holder chamber, the cassette holder chamber being loaded with a cassette, the photo film holder chamber being loaded with the photo film, and having the exposure unit secured thereto.
Thus, it is possible that plural units in which relevant elements are combined ensure suitability to recycling by disassembly and assembly, because the aperture stop actuator is included in the flash unit in contrast with the aperture stop mechanism included in the lens unit.